If a failure is generated in a communication network having a redundant structure, the communication is resumed by changing a route of the frame transfer. In relation to such a redundant structure, a transmission apparatus has been proposed which suppresses the generation of flooding in order to prevent the band of the operating network from becoming limited. An example of such a transmission apparatus has been proposed in a Japanese Laid-Open Patent Publication No. 2007-266850.
On the other hand, a frame transfer apparatus which transfers frames employs a protocol that performs a route control between apparatuses and a mechanism that recognizes a failure generated in each apparatus. For example, the Ether (registered trademark) network having the redundant structure employs a route control protocol that avoids a loop structure, such as the ring protocol and the spanning tree protocol.
In order to enable the route control protocol in the case of the ring control, the frame transfer apparatus is provided with a ring port failure detecting part, a network failure judging part to judge whether a failure is generated within the ring network, and a ring protocol part to perform various ring controls including a ring switch.
However, the frame transfer apparatus which enables the route control protocol becomes extremely expensive because the route control protocol is extremely complex, and the maintenance and operation of the communication network formed by the frame transfer apparatus becomes extremely complex.